The present invention relates to an automatically returning apparatus for a turn signal lamp switch and, particularly to an automatically returning apparatus for a turn signal lamp switch which is adapted to release a thrown switch of a turn signal lamp, thereby permitting it to automatically return to its original position.
In the prior art, there is an automatically returning apparatus for a turn signal lamp switch for vehicles adapted to release by changing an operation of the handle the turn signal lamp switch thrown for indicating in advance the direction of the vehicle when effecting an alteration of a course. However, such an automatically returning apparatus cannot apply for a vehicle without accompanying substantially a rotary operation of the handle when altering such a course, as in two-wheeled vehicle.
As a manner for releasing direction indication without accompanying the handle operation, there has been devised an idea that the direction indication is released after a certain predetermined time after throwing of a turn signal lamp switch. However, this arrangement has an inconvenience that the direction indication is released before the course alteration is completed when there is delay in effecting the course alteration. Also, in a release mechanism for a turn signal lamp switch by the handle operation mounted on a four-wheeled car, the release operation must be effected by the driver when not accompanying the changing operation indicated by the position of the handle, for example, altering the vehicle advancing course.
Further, in the prior art, there is proposed an automatically returning apparatus for a turn signal lamp switch which does not release the direction indication until the vehicle runs a certain predetermined time and distance after throwing of the turn signal lamp switch.
Such an automatically returning apparatus detects running time and running distance with a semiconductor switching circuit when the turn signal lamp switch is thrown by manual operation, thereby permitting actuation of a solenoid which drives the return of the switch.
The turn signal lamp switch conventionally used has a mechanical structure. For example, the structure is so constituted that the switch is thrown by bringing down the operating lever and moreover has a holding force exerted by a spring or the like so as to prevent release caused by oscillation or the like, or that the switch is thrown by sliding the operating lever and moreover has a holding force also exerted by a spring or the like. Accordingly, in effecting the release of such a switch, one cannot expect its sure returning operation if the solenoid for returning the switch is momentarily actuated by the aforementioned semiconductor switching circuit. This is because the aforementioned mechanical switch necessitates about 400 milliseconds (ms) in order to fully return the operating lever while the operating time of the semiconductor-switching circuit for detecting the running distance and time is 10-20 ms at the most. Therefore, the semiconductor switching circuit may fail to return the switch operating lever due to the short operating time of the switching circuit and the long operating time of the solenoid.